This invention relates to the field of retrograde coronary sinus perfusion (RCSP) devices and methods, and more particularly to steady state RCSP devices and methods.
The primary purpose for RCSP devices is to help the victims of heart attack. During a heart attack, the coronary arteries fail to provide blood to the heart muscle. This lack of oxygenated blood causes irreversible damage to the heart if continued for too long.
To prevent or minimize the damage to the heart muscle from heart attacks, RCSP devices pump oxygenated blood, and any other drugs or nutrients deemed necessary by a doctor, to the heart muscle through the coronary veins. This is counter to the normal blood flow of the heart muscle which is usually out of those veins. In the diagram of the human heart shown in FIG. 1, an RCSP device's catheter would be inserted past coronary sinus valve 1 into coronary sinus 2. The coronary sinus is a large channel for venous blood from the heart muscles.
To operate effectively, RCSP devices must be placed into proper position in the heart very quickly because damage to heart muscles from a heart attack can occur very fast, and any time lost in positioning RCSP devices might be critical to a patient.
At present, the most common device for retrograde coronary sinus perfusion is a pulsed blood flow system which pumps blood into the heart only during the heart muscle's rest cycle or diastole. The pulsed system is inactive during the heart's pumping cycle or systole. An example of such a device is shown in Farcot, J. C., et al., "Synchronized Retro Perfusion of Coronary Veins for Circulatory Support of Jeopardized Ischemic Mycardium," Am. J. Card. 41, 1191-201 (1978), and GB Patent No. 2,029,236 to Durand and Farcot. Both the patent and the article describe an RCSP system having a single-lumen catheter surrounded by a balloon. The flow of blood into the catheter's lumen or channel first inflates the balloon. This blocks the coronary sinus and enhances retrograde perfusion by ensuring that the subsequent blood flowing through the catheter goes into the coronary sinus.
One problem of this and other pulsed RCSP systems is inefficiency because viscous flow damping makes it difficult to pump blood down a small diameter catheter and into the heart at the normal heart rate. It is also difficult to start and stop the flow of blood quickly because of fluid inertia. Another problem of pulsed systems is that the pumping motion of the blood produces flow shear stress which causes hemolysis which is disintegration of red blood cells.
A second type of RCSP device is a continuous or steady-state device which pumps blood continuously through a catheter in the coronary sinus. One such device, shown in Feola et al., "A Method of Coronary Retroperfusion for The Treatment of Acute Myocardial Ischemia," Cardiovascular Disease 5:235-2430 (1978), employs a double lumen catheter inserted into the coronary sinus. A large central lumen carries blood pumped from a blood reservoir by a roller pump to the heart. A smaller lumen is connected to a pump which inflates and deflates a balloon at the tip of the catheter in synchronism with the heart rate.
While the device in Feola et al. does not have the same problem of viscous and inertial fluid damping as pulsed RCSP systems, the roller pump still tends to damage red blood cells and, by providing constant flow, may cause harm if resistance to the blood flow into the coronary sinus increases unexpectedly. In addition, since the balloon in Feola et al. is placed at the tip of the catheter, those portions of the coronary sinus between the catheter tip and the coronary sinus valve will not receive oxygenated blood or nutrients when the balloon inflates.
Accordingly, one objective of this invention is a safe and effective RCSP device.
Another objective of this invention is a simple, efficient and reliable RCSP device that minimizes hemolysis.
Yet another objective of this invention is an RCSP device which provides oxygenated blood and nutrients to much of the heart.